Environmental regulations mandate the lowering of sulfur levels in motor gasoline (mogas), for example, to 10 ppm or less. In many cases, lower sulfur levels for mogas can be achieved by hydrotreating naphtha produced from Fluid Catalytic Cracking (FCC), which is a significant contributor to sulfur in the mogas pool. Additionally, since sulfur in mogas can also lead to decreased performance of catalytic converters, a 10 ppm or less sulfur target is desirable even in cases where regulations would permit higher levels.
Conventional fixed bed hydrotreating is used to desulfurize (remove sulfur from) naphtha to reduce the sulfur content to very low levels. However, such hydrotreating also results in significant octane number loss due to extensive reduction of the olefin content in the naphtha. Techniques are needed to reduce not only the sulfur level in naphtha but also to minimize or eliminate the reduction of beneficial properties such as octane number preferably while minimizing additional equipment and/or operational cost.
Accordingly, it is desirable to provide apparatuses and methods for desulfurization of naphtha while substantially preserving or enriching the olefin content of the naphtha. Additionally, it is desirable to provide apparatuses and methods for desulfurization of naphtha while minimizing additional equipment and/or operational cost. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.